limbic system Flashcards
limbic lobe composed of
a more primitive portion of the cortex, and it includes the:
- cingulate gyrus,
- retrosplenial gyrus,
- subcallosal gyrus, and
- parahippocampal gyrus
limbic lobe definition
- introduced by Broca
- telencephalic structures that circle the foramen of Monro and border diencephalon
- comprised of gray matter
limbic system definition
- structures that interface between the cortex and the hypothalamus and modulate the motivational and emotional functions initiated by the hypothalamus
- includes all structures that are linked to limbic lobe that project to hypothalamus or its targets
limbic system function
- receive cortical input and modulate hypothalamic functions
- control of emotion, motivated behavior, and memory
observations of limbic system clinically
- lesion: results in no paralysis or sensory deficits
- seizure/electrical: do no produce clonic movements or sensory perceptions
- excitation: evokes emotional states or memory fragments
anatomy of hippocampus
papez circuit
- controls motivation and emotion
- Start: hippocampus (HPC) interlocking cell layers.
- Output = fornix
- Fornix > mammillary bodies > anterior nucleus of the thalamus via the mammillothalamic tract (MThT)
- fibers > internal capsule to the cingulate
gyrus - Cingulate gyrus > the entorhinal cortex >
hippocampus.
See slides 12-20 for cross section images and labels
Henry Molaison
- removal of hippocampus to prevent spreading of seizures
- symptoms: Severe memory deficit, Loss of memory consolidation, No emotional issues
declarative memory
- short term memory consolidated to long term memory
- if you study it will be short term but repetitively it will be consolidated into long term memory
place cells of hippocampus
- if you have an issue with short term memory (like HM after removal of hippocampus) you will still have long term memory
- you can still navigate places from long term memory, but won’t be able to use short term memory
role of hippocampus
- memory consolidation
- spatial navigation
uncus
- next to the parahippocampal gyrus
- Inside the uncus is the amygdala
- Uncus = hook
location of amygdala in cross section
amygdala pathways
- stria terminalis
- ventral amydalofugal pathway
major inputs and outputs of amygdala
- hypothalamus
- brainstem
- hippocampus and entorhinal cortex
- mediodorsal nucleus of thalamus
- anterior cingulate cortex
- prefrontal cortex
- olfactory tract
role of amygdala
the integrative center for emotions, emotional behavior, and motivation
Kluver-Bucy syndrome
- removal of amygdala
symptoms: - Tameness
- loss of fear and other emotional reactions
- hypersexual
- bulimia
- Toral tendencies
- hypermetamorphosis: short attention span
amygdala can also cause/have:
- temporal lobe epilepsy
- lesions
temporal lobe epilepsy symptoms
- aggression
- panic attacks
lesions of amygdala symptoms
- placidity
- flatness of affect
- failure to discriminate emotional expressions
- loss of emotional memory processing